The present invention relates to aromatic formaldehyde condensation products which are substantially colourless and water-soluble and contain sulphonate and/or carboxylate groups.
Water-soluble aromatic formaldehyde condensation products are known per se (see Ullmanns Enzyklopadie der technischen Chemie (Ullmann's encyclopaedia of technical chemistry) Volume 16 (1979), pages 140 et seq.) and can be prepared by the processes reported on there or by processes such as are described, for example, in Houben-Weyl: "Methoden der organischen Chemie" (Methods of organic chemistry) Volume 14/2, pages 263-292, G. Thieme Verlag Stuttgart (1963), or in German Offenlegungsschrift 1,960,616 and German Offenlegungsschrift 1,961,369.
However, the known aromatic formaldehyde condensation products have a strong intrinsic colour, which has proved very disadvantageous, particularly when these products are used in the textile field.